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43. Creating Your Own Modules

1. Introduction​

A module is just a Python file with functions, variables, or classes.
Creating your own modules helps organize code.

2. Creating a Module​

  1. Create a file mymath.py:
def add(a, b):
    return a + b
def subtract(a, b):
    return a - b
  1. Use it in another file:
import mymath
print(mymath.add(2,3))

3. Module Search Path​

Python looks for modules in:

  • Current directory
  • PYTHONPATH environment variable
  • Standard library path
import sys
print(sys.path)

4. Organizing with Packages​

A package is a directory with an __init__.py file.
Example structure:

mypackage/
    __init__.py
    module1.py
    module2.py

Use:

from mypackage import module1

5. Best Practices​

  • Use lowercase filenames.
  • Group related functions in one module.
  • Keep modules small and focused.

6. Next Steps​

✅ You now know how to create your own modules.
In the next chapter, we’ll revisit virtual environments.